Add Windows Phone Metro theme system

Color system:
- Dark (#1F1F1F bg), Light (white bg), AMOLED (pure black bg)
- All 20 WP8 accent colors (Lime through Taupe)
- User-selectable accent color persisted in DataStore
- Default: Cobalt (#0050EF)

Typography (WP scale):
- 54sp Light for page titles, 32sp Light for pivot headers
- 24sp Light for section headers, 17sp body, 15sp normal, 14sp small
- SemiBold for emphasis, Light for large display text

Flat surfaces only — no elevation, no tonal surfaces, no Material chrome.

Co-Authored-By: Claude Opus 4.6 (1M context)

Signed-off-by: Avinal Kumar <avinal.xlvii@gmail.com>

composeApp/src/commonMain/kotlin/com/avinal/memos/ui/theme/Color.kt

@@ -0,0 +1,101 @@
+package com.avinal.memos.ui.theme
+
+import androidx.compose.material3.ColorScheme
+import androidx.compose.material3.darkColorScheme
+import androidx.compose.material3.lightColorScheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.compositionLocalOf
+import androidx.compose.ui.graphics.Color
+
+val PriorityP1 = Color(0xFFE51400)
+val PriorityP2 = Color(0xFFF0A30A)
+val PriorityP3 = Color(0xFF1BA1E2)
+val LabelGreen = Color(0xFF60A917)
+val DuePurple = Color(0xFF6A00FF)
+val OverdueRed = Color(0xFFE51400)
+
+// --- WP8 Accent Colors ---
+data class AccentColor(val name: String, val color: Color)
+
+val WpAccentColors = listOf(
+    AccentColor("Lime", Color(0xFFA4C400)),
+    AccentColor("Green", Color(0xFF60A917)),
+    AccentColor("Emerald", Color(0xFF008A00)),
+    AccentColor("Teal", Color(0xFF00ABA9)),
+    AccentColor("Cyan", Color(0xFF1BA1E2)),
+    AccentColor("Cobalt", Color(0xFF0050EF)),
+    AccentColor("Indigo", Color(0xFF6A00FF)),
+    AccentColor("Violet", Color(0xFFAA00FF)),
+    AccentColor("Pink", Color(0xFFF472D0)),
+    AccentColor("Magenta", Color(0xFFD80073)),
+    AccentColor("Crimson", Color(0xFFA20025)),
+    AccentColor("Red", Color(0xFFE51400)),
+    AccentColor("Orange", Color(0xFFFA6800)),
+    AccentColor("Amber", Color(0xFFF0A30A)),
+    AccentColor("Yellow", Color(0xFFE3C800)),
+    AccentColor("Brown", Color(0xFF825A2C)),
+    AccentColor("Olive", Color(0xFF6D8764)),
+    AccentColor("Steel", Color(0xFF647687)),
+    AccentColor("Mauve", Color(0xFF76608A)),
+    AccentColor("Taupe", Color(0xFF87794E)),
+)
+
+val LocalAccentColor = compositionLocalOf { Color(0xFF0050EF) }
+
+// --- Metro Theme Variants ---
+enum class MetroTheme(val label: String) {
+    DARK("dark"),
+    LIGHT("light"),
+    AMOLED("amoled"),
+}
+
+fun metroColorScheme(theme: MetroTheme, accent: Color): ColorScheme = when (theme) {
+    MetroTheme.DARK -> darkColorScheme(
+        background = Color(0xFF1F1F1F),
+        onBackground = Color.White,
+        surface = Color(0xFF1F1F1F),
+        onSurface = Color.White,
+        surfaceVariant = Color(0xFF2A2A2A),
+        onSurfaceVariant = Color(0xFF999999),
+        primary = accent,
+        onPrimary = Color.White,
+        secondary = Color(0xFF333333),
+        onSecondary = Color(0xFFCCCCCC),
+        error = Color(0xFFE51400),
+        onError = Color.White,
+        outline = Color(0xFF666666),
+        outlineVariant = Color(0xFF444444),
+    )
+    MetroTheme.LIGHT -> lightColorScheme(
+        background = Color.White,
+        onBackground = Color.Black,
+        surface = Color.White,
+        onSurface = Color.Black,
+        surfaceVariant = Color(0xFFF0F0F0),
+        onSurfaceVariant = Color(0xFF666666),
+        primary = accent,
+        onPrimary = Color.White,
+        secondary = Color(0xFFE8E8E8),
+        onSecondary = Color(0xFF333333),
+        error = Color(0xFFE51400),
+        onError = Color.White,
+        outline = Color(0xFFCCCCCC),
+        outlineVariant = Color(0xFFE0E0E0),
+    )
+    MetroTheme.AMOLED -> darkColorScheme(
+        background = Color.Black,
+        onBackground = Color.White,
+        surface = Color.Black,
+        onSurface = Color.White,
+        surfaceVariant = Color(0xFF111111),
+        onSurfaceVariant = Color(0xFF999999),
+        primary = accent,
+        onPrimary = Color.White,
+        secondary = Color(0xFF1A1A1A),
+        onSecondary = Color(0xFFCCCCCC),
+        error = Color(0xFFE51400),
+        onError = Color.White,
+        outline = Color(0xFF555555),
+        outlineVariant = Color(0xFF333333),
+    )
+}

composeApp/src/commonMain/kotlin/com/avinal/memos/ui/theme/Theme.kt

@@ -0,0 +1,27 @@
+package com.avinal.memos.ui.theme
+
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.graphics.Color
+import com.avinal.memos.util.LocalAppDependencies
+
+@Composable
+fun MemosAppTheme(content: @Composable () -> Unit) {
+    val deps = LocalAppDependencies.current
+    val themeName by deps.tokenStore.theme.collectAsState(initial = "DARK")
+    val accentName by deps.tokenStore.accentColor.collectAsState(initial = "Cobalt")
+
+    val metroTheme = try { MetroTheme.valueOf(themeName) } catch (_: Exception) { MetroTheme.DARK }
+    val accent = WpAccentColors.find { it.name == accentName }?.color ?: Color(0xFF0050EF)
+
+    CompositionLocalProvider(LocalAccentColor provides accent) {
+        MaterialTheme(
+            colorScheme = metroColorScheme(metroTheme, accent),
+            typography = MetroTypography,
+            content = content,
+        )
+    }
+}

composeApp/src/commonMain/kotlin/com/avinal/memos/ui/theme/Type.kt

@@ -0,0 +1,24 @@
+package com.avinal.memos.ui.theme
+
+import androidx.compose.material3.Typography
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.sp
+
+val MetroTypography = Typography(
+    displayLarge = TextStyle(fontSize = 54.sp, fontWeight = FontWeight.Light, letterSpacing = (-0.5).sp),
+    displayMedium = TextStyle(fontSize = 32.sp, fontWeight = FontWeight.Light, letterSpacing = 0.sp),
+    displaySmall = TextStyle(fontSize = 24.sp, fontWeight = FontWeight.Light, letterSpacing = 0.sp),
+    headlineLarge = TextStyle(fontSize = 32.sp, fontWeight = FontWeight.Light, letterSpacing = 0.sp),
+    headlineMedium = TextStyle(fontSize = 24.sp, fontWeight = FontWeight.Light, letterSpacing = 0.sp),
+    headlineSmall = TextStyle(fontSize = 19.sp, fontWeight = FontWeight.Normal, letterSpacing = 0.sp),
+    titleLarge = TextStyle(fontSize = 24.sp, fontWeight = FontWeight.Light, letterSpacing = 0.sp),
+    titleMedium = TextStyle(fontSize = 17.sp, fontWeight = FontWeight.SemiBold, letterSpacing = 0.sp),
+    titleSmall = TextStyle(fontSize = 15.sp, fontWeight = FontWeight.SemiBold, letterSpacing = 0.sp),
+    bodyLarge = TextStyle(fontSize = 17.sp, fontWeight = FontWeight.Normal, letterSpacing = 0.sp),
+    bodyMedium = TextStyle(fontSize = 15.sp, fontWeight = FontWeight.Normal, letterSpacing = 0.sp),
+    bodySmall = TextStyle(fontSize = 14.sp, fontWeight = FontWeight.Normal, letterSpacing = 0.sp),
+    labelLarge = TextStyle(fontSize = 15.sp, fontWeight = FontWeight.SemiBold, letterSpacing = 0.sp),
+    labelMedium = TextStyle(fontSize = 14.sp, fontWeight = FontWeight.Normal, letterSpacing = 0.sp),
+    labelSmall = TextStyle(fontSize = 12.sp, fontWeight = FontWeight.Normal, letterSpacing = 0.sp),
+)